The situation is that my Macbook Pro's disk drive doesn't work. It just rejects a lot of CDs or DVDs you put in there. I've partitioned the hard drive using Disk Utility, so now i have 225GB of OS X and 25GB of an empty FAT partition. I have a USB with the contents of the windows xp install disk burned to it. I try and hold down alt when restarting, but my usb doesn't come up as one of the options. What can i do to allow it to boot from my usb, and thus install windows?
Just make an USB installer on a flash drive. Your USB drive needs to be bootable. You could use e.g. WinToFlash Use boot camp tool on OSX to prepare your HDD not manually with disk util.
If you crash into problems booting the installer from USB but you're sure it's a bootable flash drive you have to use rEFIt